A spin treatment apparatus according to an embodiment performs a treatment while rotating a substrate and includes: at least three clamp pins configured to contact an outer peripheral surface of the substrate and clamp the substrate; rotatable pin rotators provided for the respective clamp pins and each configured to retain the corresponding clamp pin at a position offset from a rotation axis of the pin rotator parallel with a rotation axis of the substrate; magnet gears provided for the respective pin rotators around outer peripheral surfaces thereof and each having a magnetic-pole part formed spirally about the rotation axis of the pin rotator; rotation magnets provided for the respective magnet gears and positioned to attract and be attracted by the magnetic-pole part of the corresponding magnet gear; and a movement mechanism configured to move the rotation magnets along the rotation axes of the pin rotators.